docs: document data_app tile in dashboards-as-code

guides/developer/dashboards-as-code.mdx

@@ -472,7 +472,7 @@ tiles:
     type: markdown
     properties:
       title: My cool dashboard
-      hideTitle: false
+      hideFrame: false # Set to true to hide the markdown tile's frame
       content: |- # Markdown tiles have their config stored here under 'content'.
         This is an example of a markdown tile
 
@@ -483,6 +483,25 @@ tiles:
         - points
 
         And so on...
+  - x: 0
+    "y": 11
+    h: 2
+    w: 36
+    tabUuid: null
+    type: heading
+    properties:
+      text: Sales overview
+      showDivider: true # Renders a horizontal divider below the heading
+  - x: 0
+    "y": 13
+    h: 6
+    w: 36
+    tabUuid: null
+    type: data_app
+    properties:
+      title: Sales explorer
+      hideTitle: false
+      appUuid: 1a2b3c4d-5e6f-7890-abcd-ef1234567890 # UUID of the data app to embed
 filters: 
   # Filters are split by whether they are performed 
   # on a metric, dimension or table calculation. 
@@ -543,6 +562,42 @@ verified: true
 # See /guides/verified-content for full semantics.
 ```
 
+#### Tile types
+
+Each tile in the `tiles:` list has a `type` and a matching `properties` object. The supported tile types and their writable properties are:
+
+| `type` | Properties |
+| --- | --- |
+| `saved_chart` | `title`, `hideTitle`, `chartSlug` |
+| `sql_chart` | `title`, `hideTitle`, `chartSlug` |
+| `markdown` | `title`, `hideFrame`, `content` |
+| `loom` | `title`, `hideTitle`, `url` |
+| `heading` | `text`, `showDivider` |
+| `data_app` | `title`, `hideTitle`, `appUuid` |
+
+A few things worth calling out:
+
+- **Markdown tiles** use `hideFrame` (not `hideTitle`) to hide the tile's frame. The title is set via the `title` property.
+- **Heading tiles** support `showDivider: true` to render a horizontal divider line below the heading text — useful for visually separating sections of a dashboard.
+- **Data app tiles** reference an existing [data app](/guides/data-apps) by its `appUuid`. The data app itself isn't managed as code, so make sure the referenced app exists in the target project before uploading. To find the `appUuid`, open the data app in Lightdash and copy it from the URL.
+
+#### Tabs
+
+If your dashboard uses tabs, each tab can be configured with these properties:
+
+```yml
+tabs:
+  - uuid: 7b1c2d3e-4f56-7890-abcd-ef1234567890
+    name: Overview
+    order: 0
+  - uuid: 8c2d3e4f-5678-90ab-cdef-1234567890ab
+    name: Internal metrics
+    order: 1
+    hidden: true # Hides the tab from the tab bar while keeping its tiles in the file
+```
+
+Set `hidden: true` to keep a tab's content in the file but hide it from the tab bar in the UI — handy for drafting or temporarily archiving a section without deleting it.
+
 ### Charts
 
 Charts store a large amount of configuration, and so are more complex and more variable that what you will find within the dashboard yml files.